Roller pump in an extra corporeal support system

ABSTRACT

An extracorporeal support system has an inlet catheter which is positioned with its distal end in the right atrium or vena cava of the patient. A roller pump with an inlet pressure sensor is positioned close to its inlet to sense the pressure in the inlet line which pumps the blood through the system to any output catheter positioned in the arterial system of the patient. The system has a shunt with blocking valves to block the flow automatically in the event of an unsafe condition. The system has a microprocessor-based controller for automatic operation of the system components including a servomotor for driving the roller pump at a speed to precisely maintain the inlet pressure at a preselected point. The system includes a blood treatment device such as an oxygenator. The roller pump has an axially adjustable head which is also removable.

BACKGROUND OF THE INVENTION

1. Field

This invention relates to support systems suitable for treating theblood of a patient outside of the body and returning the blood to thebody as part of a medical treatment or life support activity. Thisinvention also includes a roller pump for use in the support system.

2. State of the Art

Today a variety of medical treatments involve procedures by which theblood of a patient is processed through an external or extracorporealsystem. For example, the blood may be removed for dialysis or foroxygenation.

In the same vein, various surgical procedures involving the heart mayrequire diversion of the blood from the cardiopulmonary system untilcompletion of the involved surgical procedures.

Systems for extracorporeal support of a patient are known. For exampleU.S. Pat. No. 4,662,355 (Pieronne) discloses a pump regulation systemwhich may be used for regulation of the bypass circuit of an artificialkidney and a cardiopulmonary system. Various components for use in suchsystems are available commercially. For example, Seabrook MedicalSystems, Inc. of Cincinnati, Ohio offers a blood warming unit forwarming the blood before it is returned to the patient and a bladderholder for use as an inlet reservoir for a pump. Seabrook MedicalSystems, Inc. also offers a pump controller as well as a cart formounting or positioning selected components of an extracorporeal supportsystem.

Canyon Medical Products of Salt Lake City, Utah offers percutaneousfemoral bypass cannulation systems which may be suitable forinterconnecting extracorporeal support systems to a patient.Stockert-Shiley of Irvine, Calif. offers pressure control modules foruse in extracorporeal support systems. C. R. Bard, Inc. of Billerica,Mass. even offers a complete extracorporeal cardiopulmonary supportsystem as a commercial product.

Commercial components and systems available today have typically beenavailable for adult patients and some infants. Newborns may needtemporary cardiopulmonary support when suffering respiratory failure ora fulminant disease leading to respiratory failure. Extracorporealsupport for newborns (neo-nates) has been successfully employed for over10 years. The procedure has been described in several professionaljournals. R. H. Bartlett, et al., EXTRA CORPOREAL MEMBRANE OXYGENATION(ECMO) CARDIO-PULMONARY SUPPORT IN INFANCY, Trans. Amer. Soc. Artif.Int. Organs, 1976, p. 80-93 (Vol. XXII); R. H. Bartlett, et al., EXTRACORPOREAL CIRCULATION (ECMO) IN NEO-NATAL RESPIRATORY FAILURE, Jnl. ofThor. and Card. Surgery, 1977, p. 826-33 (Vol. 74, No. 6); L. Gattinoni,et al., REVERSAL OF TERMINAL ACUTE RESPIRATORY FAILURE BY LOW FREQUENCYPOSITIVE PRESSURE VENTILATION WITH EXTRA CORPOREAL REMOVAL OF CO₂(LFPPV-ECCO₂ R), Trans. Am. Soc. Artif. Internal Organs, 1981, p.289-93, (Vol. XXVII); and W. Fukui, et al., A PORTABLE, PUMPLESS, AVBY-PASS ECCO₂ R SYSTEM WITH A HOLLOW FIBER MEMBRANE LUNG, 1986, Tran.Soc. Artif. Internal Organs, p. 521-24 (Vol. XXXII).

Extracorporeal support for neonates is monitored by a national centralregistry. It now has recorded data for over 1800 patients receiving suchtreatment. Notably, newborns have rather small blood volume (e.g. 1liter or less) and are therefore quite difficult to treat because anexternal support system requires a volume of blood to work. Further, anyextracorporeal support system inherently involves the use of substantialamounts of heparin in order to minimize clotting, not only in the systembut also internally within the patient. As a result, it is presentlyunderstood that extracorporeal support of neonates has been limited tothose weighing approximately more than 2 kilograms and who are typicallymore than 35 weeks gestation at birth. Nonetheless, there are aconsiderable number of neonates who are candidates for extracorporealsupport, but who are not of sufficient size to successfully undergotreatment.

It is presently understood that many of the neonates who qualify for thetreatment are inherently poor risks for transport. Nevertheless, many ofthe neonate patients reported to the national central registry were bornaway from the treating center and were necessarily transported. Underthese circumstances, there is a compelling and growing need for anextracorporeal support system to deal with neonates presentlyuntreatable and to improve the ability to transport all neonates. Thatis, there is a need for a more regulated, automated and moretransportable extracorporeal support system. Notably, such a systemwould also be suitable for use not only with neonates but also witholder patients, particularly those requiring transport. Further, ahighly automated system may be desirable for use with all patients,regardless of age, because of the reduced involvement of attendantpersonnel in, for example, an intensive care unit (ICU). Additionally, asmaller and more compact system is desirable to reduce or minimize therisks of contamination from a larger system, and because of an increasedneed for heparin and the increased potential for hemolysis.

Efforts heretofore to miniaturize have been attempted. T. Kawamuri etal., EXTRA CORPOREAL MEMBRANE OXYGENATION (ECMO) IN PUMPLESS RIGHTVENTRICLE TO LEFT ATRIUM BY-PASS, 1985 Trans. Am. Soc. Artif. Intern.Organs, p. 616-620 (Vol. XXXI). The reported miniaturized system usedthe pressure gradient between the arterial and venous systems. However,in many circumstances, particularly in the context of an asphyxiatedmyocardium, such a pumpless system is believed to be inapplicable orunsuitable. Further, the devices described did not appear to be suitablefor long-term use and became routinely nonfunctional after 24 to 48hours when in typical neonate applications, the extracorporeal supportmay be required for periods up to 130 hours, if not more.

SUMMARY OF THE INVENTION

An extracorporeal support system has an inlet positioned to receiveblood from the patient. Conduit means preferably of substantiallyconstant diameter is provided to transport blood between the inlet andan outlet. The outlet is positioned to return the blood to the patient.Roller pump means is interconnected in the conduit means and configuredto pump the blood through the conduit means. The roller pump meansincludes a motor to effect operation.

An inlet detecting means is interconnected in the conduit means betweenthe inlet and the roller pump means to measure the pressure of the bloodin the conduit means and to supply a signal reflective of the inletblood pressure in the conduit means. Blood treatment means isinterconnected in the conduit means downstream of the pump means toreceive and treat the blood and also to supply the blood at its output.Control means is interconnected to the inlet detecting means to receivethe signal reflective of the inlet blood pressure. It is also connectedto the motor means to supply operation signals thereto. The controlmeans supplies operation signals which vary the motor speed between astop condition upon receipt of a signal reflective of a preselected"low" inlet blood pressure and a preselected high speed condition uponreceipt of signal reflective of a preselected "high" inlet bloodpressure.

In one embodiment, an upstream pressure detector is interconnected inthe conduit means between the roller pump means and the blood treatmentmeans; and a downstream pressure detector is interconnected in theconduit means between the outlet and the blood treatment means. Theupstream and downstream pressure detectors each measure the pressures ofblood in their respective locations and supply signals reflective of theblood pressure to the control means which in turn generates alarmsignals when either one or both of the detected pressures differ frompreselected pressures.

In another embodiment, an air detector is interconnected in the conduitmeans between the blood treatment means and the outlet means. The airdetector detects the presence of air in the conduit means and generatesa signal reflective thereof. The control means receives the signalreflective of air in the conduit means to generate an alarm signal. In apreferred arrangement, a shunt is interconnected in the conduit means atone end between the inlet and the inlet detecting means and at the otherend between the blood treatment means and the outlet. A first solenoidvalve means is interconnected between the shunt and the inlet, a secondsolenoid valve is interconnected in the shunt and the third solenoidvalve is interconnected between the outlet and the shunt. Upon detectionof air, the control means generates and sends operating signals to thefirst and third solenoid valves to block fluid flow in the conduit meansand to the second solenoid valve to allow fluid flow through the shunt.

In an alternate embodiment, a second pump means is interconnected intothe conduit means between the inlet means and the outlet means formetering fluids into the blood. Preferably it is interconnected betweenthe roller pump means and the blood treatment means. The second pumpmeans is desirably a syringe to insert fluids into the conduit means.Most preferably, the second pump means includes a motor deviceconductively connected to the control means to receive signals therefromto operate the motor device and meter the fluid into the conduit.

The roller pump means of the extracorporeal support system preferablyincludes a housing with a top, bottom and front. The housing has akeyhole-shaped recess formed in the top extending inwardly therefrom.The recess has a throat with opposite sides opening through the frontinterconnecting with opposite ends of an arcuate recessed surface. Axlemeans is rotatably secured to the housing and extends into the recesssubstantially positioned with respect to the arcuate recessed surface.

Pump head means is removably secured to the axle means within therecess. The pump head means includes roller means positioned proximatethe arcuate recessed surface for urging the conduit means against thearcuate recessed surface. The pump head means also includes lockingmeans for removably securing the pump head to the axle.

Desirably, the locking means includes an engagement portion and a latchmember positioned for operation by the user and operable between thefirst position in which the latch member engages the engagement portionto secure the pump to the axle means and a second position in which thelatch member is disengaged from the engagement portion so that the pumphead may be removed from the axle means.

In a preferred embodiment, adjustment means is interpositioned betweenthe pump head means and the axle means for moving the pump head meansaxially toward and away from the axle means and in turn moving theroller means toward and away from the arcuate recessed surface.

Preferably, the adjustment means includes a follower positioned to movetoward and away form the axle means and a screw means with a headaccessible to the user. The screw means has threaded portionsinterconnecting the follower to the axle. The screw means is operable bythe user to move the follower toward and away from the axle.

Desirably, the pump head means includes a sleeve for positioning overthe follower. The engagement portion includes a key way formed partly inthe sleeve and partly in the follower. The latch is desirably a keyinsertable into and removable from the key way. The arcuate recessedsurface preferably slants toward the axle means. The roller meansincludes a plurality of rollers each conically shaped with an exteriorsurface positioned substantially tangentially proximate the arcuaterecessed surface.

The pump head means preferably has a central member for connection tothe axle. A top member is connected to the central member with a handlerotatably connected thereto and moveable between the first position inwhich the handle extends away from the pump head means and is operableby the user to rotate the pump head means and a second position in whichthe handle is positioned in a stored configuration proximate the topmember.

In yet another arrangement, the pump head means includes a base membersecured to the central member and the roller means is a pair of rollerspositioned substantially diametrically opposite each other between thetop member and the base member. The lock member is preferably positionedin the front and operable by the user to secure the conduit means to theside of the throat. It is also preferable that the motor means be aservomotor connected to rotate the axle means.

The inlet detecting means of the extracorporeal support system includesan interconnect section for interconnection in the conduit means. Anaperture is formed in the interconnect section with a membrane sealinglysecured thereto over the aperture for movement inwardly and outwardlywith respect to the aperture. A housing is sealingly secured to theinterconnect section over the aperture and filled with a liquid. Aplunger is positioned within the housing and operable between the firstposition in which it is in contact with the membrane urging it into theinterconnect section and a second position in which it is spaced awayfrom the membrane. The solenoid is positioned proximate the plunger andoperable to move the plunger between the first and second positions. Aport is also formed in the housing with a pressure sensor connectedthereto to sense the pressure of the liquid in the housing as reflectedby movement of the membrane to generate signals reflective thereof atits output. The interconnect section preferably has an inlet and outletwith connecting means at the inlet and the outlet for interconnectionwithin the conduit means. The plunger desirably has an arcuate head tocontact with the membrane positioned at the end of a shaft. The solenoidis positioned along the shaft. A spring is preferably positioned to urgethe plunger to and away from the membrane.

The solenoid valve means may desirably be fluid flow blocking clampshaving a base with a rotary solenoid secured thereto and electricallyconnected to receive operating signals. An axle is secured to therotating solenoid to extend away therefrom. A frame is secured to theaxle with a roller secured thereto spaced away from the axle androtatable to a first position proximate a stationary member to clamp theconduit means positioned thereinbetween, and to a second position inwhich the roller is rotated away from the stationary member. Thestationary member is secured to the base with the roller moving relativethereto.

A method of extracorporeal support is also disclosed in which the systemcomponents are assembled and put into operation to effect a bloodsupport operation.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, which illustrate the best mode presently contemplatedfor carrying out the invention:

FIG. 1 is a simplified system diagram of an extracorporeal supportsystem of the instant invention;

FIG. 2 is a perspective view of a roller pump for use in anextracorporeal support system of the instant invention;

FIG. 3 is a top view of the roller pump of FIG. 2;

FIG. 4 is a cross-sectional view of the roller pump of FIG. 2;

FIG. 5 is a perspective view of the roller pump of FIG. 2 in aconfiguration for manual operation;

FIG. 6 is a partial perspective cut-away-view of a portion of a rollerpump housing;

FIG. 7 is a cross-sectional view of a block for use with the roller pumpin the configuration illustrated in FIG. 6;

FIG. 8 is a top or plan view of a key for use with the roller pump ofFIG. 2;

FIG. 9 is a cross-sectional view of a pressure detector for use in theextracorporeal support system of the instant invention;

FIG. 10A is a partial cross-sectional depiction of a solenoid valvemeans for use in the extracorporeal support system of the instantinvention;

FIG. 10B is a plan view of the top of the solenoid valve means of FIG.10A;

FIG. 11 is a partial cross-sectional depiction of the solenoid valvemeans of FIG. 10;

FIG. 12 is a simplified block diagram of a control means of anextracorporeal support of the instant invention;

FIG. 13 is a front view of the control panel of the control meansillustrated in FIG. 12 for use in the extracorporeal support system ofthe instant invention;

FIG. 14 is a circuit diagram of a watch-dog circuit for use in thecontrol means of the FIG. 12;

FIG. 15 is a clock circuit for use in the control means of FIG. 12;

FIG. 16 is a microprocessor arrangement for use in the control means ofFIG. 12;

FIG. 17 is the input and output circuitry associated with themicroprocessor of FIG. 16;

FIGS. 18A and 18B illustrate the alarm circuitry of the control means ofFIG. 12;

FIGS. 19A and 19B show input signal circuitry associated with thecontrol means of FIG. 12;

FIG. 20 shows alarm circuitry for use in the control means of FIG. 12;

FIG. 21 shows a motor speed control for use in the control means of FIG.12;

FIG. 22 shows the pressure transducer amplifier for use in the controlmeans of FIG. 12;

FIG. 23 shows an output signal buffer for use in the control means ofFIG. 12; and

FIGS. 24 through 29 show the flow diagram of the logic within themicroprocessor circuit of the control means of FIG. 12.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENT

A block diagram representative of an extracorporeal support system isdepicted in FIG. 1. The system functions to remove blood from a patient10 more specifically from the venous system of that patient. The bloodis then pumped through the system to a blood treatment device such as anoxygenator and returned to the patient 10 and more specifically to thearterial system of the patient.

In the system of FIG. 1, the blood is removed from the patient 10 andmore specifically the arterial system depicted by a vein 12. Blood isremoved by inlet means here shown to be a catheter 14 which is insertedinto the patient so that distal end 16 of the catheter 14 is positionedpreferably in the vicinity of the heart of the patient and morespecifically in the vena cava or right atrium. The vena cava or rightatrium 18 acts as a small bladder or reservoir into which the patient'sblood may collect for direct supply to the heart via a vein 20. Theblood of the patient is removed from this region via the catheter tominimize the risk of collapsing any blood vessels, to minimize abnormalflow and to minimize evacuation from any other region.

The catheter 14 has a proximal end 22 which is positioned exterior thepatient with a connector 24 for interconnection to conduit means hereillustrated as a hollow tube 26 to transmit the blood from the catheter14 into the system as hereinafter further described.

The catheter 14 acts as an inlet means to receive the blood of thepatient. The conduit means does not have any bladders or reservoirsformed in it or connected in it. By eliminating the bladders of theprior art, the total blood volume in the system is reduced along withthe risks attendant thereto. Insertion of the distal end 16 of catheter14 into the vena cava employs the natural venous reservoir for thesystem reservoir. Thus, a notable head to keep a bladder full iseliminated so a bladder or reservoir may be eliminated. Further, theselection of the vena cava or right atrium as the reservoir allowsselection of a considerably shorter length 25 (e.g. about 1/2 meter) ofinlet tube section 27. Similarly the entire conduit means maybe markedlyshort and in total from connector 24 to connector 39 may be about 2meters. The short lengths of tube reduce time of travel of blood fromconnector 24 to connector 39 and in turn reduce the heat loss so that apreheater to reheat the blood before its return to the body iseliminated. The fewer system elements and short lengths reduce the riskof clotting, of contamination and hemolysis thereby enhancing thetherapy and reducing the attendant risk of system use.

In this embodiment the conduit means is desirably flexible Tygon® tubingor other medically acceptable flexible tubing of substantially constantdiameter to transport the blood throughout the entire system. As hereillustrated, the conduit means, more particularly, the tube 26 iscomprised of numerous segments between various components which areeither connected to or interconnected in the tube 26 as more fullydiscussed hereinafter.

The system of FIG. 1 includes a roller pump means which is roller pump28. It has the conduit means and more particularly the tube 26 extendingor positioned therethrough as more fully discussed hereinafter. Theroller pump 28 is configured for pumping blood through the tube 26 andis preferably driven by motor means.

Inlet detecting means is interconnected in the conduit means and moreparticularly in the tube 26 between the catheter 14 and the roller pump28. The inlet detecting means as here illustrated is a pressure detector30 which detects the pressure of the blood in the tube 26 and suppliessignals reflective of the inlet blood pressure in the tube 26 to thecontrol means 44.

The system of FIG. 1 includes blood treatment means 32 interconnected inthe tube 26 downstream of the roller pump 28. The treatment means treatsthe blood and supplies the blood 34 through its outlet to outlet means.The outlet means, as illustrated in FIG. 1, is a catheter 36 similar tocatheter 14 having a distal end 38 and a proximal end 40. The distal end38 is positioned in the arterial system 42 of the patient 10 andpreferably in the aorta proximate the heart. The proximal end 40 isconnected to the tube 26 at connector 39 to receive the blood from theoutput of the blood treatment means 32. Thus, the blood is received bythe system through the inlet means and urged through the system andthrough the treatment means for eventual return through the outlet meansto the patient from which the blood was extracted by the roller pumpmeans.

The system of FIG. 1 further includes control means which is controller44 interconnected to the inlet detecting means and more particularly thepressure sensor 30 by a conductor (not shown for clarity) to receivesignals reflective of the inlet blood pressure. The controller 44 isalso connected to the motor means (not shown for clarity) of the rollerpump means and more particularly roller pump 28 to supply operationsignals thereto. The controller 44 supplies the operation signals tovary the motor speed between a stop condition in which the motor isstopped upon the receipt of a signal from the inlet detecting means andreflective of a preselected "low" inlet blood pressure and a preselectedhigh speed upon receipt of a signal from the inlet detecting meansreflective of a preselected "high" inlet blood pressure.

In effect the pressure sensor is positioned proximate the inlet 64 ofthe roller pump 28 to sense the pressure immediately upstream from theroller pump 28. The inlet pressure is thus transmitted to the controller44 which varies the speed of the roller pump 28 to control the pressuresensed by the pressure sensor 30 about a preselected pressure which isselected by the user so that the volume of blood available in thepatient 10 is not exhausted accidentally and so that the blood flow inthe system will be relatively constant. At the same time, the pressuredetector 30 acts as a guardian to preclude accidental excessiveevacuation of blood from the patient by sending signals to thecontroller, which in fact then regulates the roller pump 28 to eitherspeed up or slow down as necessary to maintain the blood pressure in thetube 26 and in turn in the atrium or vena cava 18 within desiredparameters selected based on the patient being treated.

The system of FIG. I further includes an upstream pressure detectorwhich is pressure sensor 46 and a downstream pressure detector which ispressure sensor 48. Both the upstream pressure sensor and downstreampressure sensor are conductively connected to the control means byconductors (not shown for clarity) to supply signals reflective of thepressure upstream of the blood treatment means and downstream of theblood treatment means respectively to the control means 44. In FIG. 1,the controller receives the signals from the upstream pressure sensor 46and downstream pressure sensor 48 causing the controller to visuallydisplay upstream and downstream blood pressures for the user and togenerate an alarm when either or both differ from a preselected setting.

The system of FIG. 1 also includes a filter 50 interconnected in thetube 26 downstream of the downstream pressure detector 48 to filter theblood before it returns to the patient to avoid accidental transmissionof any material from the blood treatment means to the patient.

In FIG. 1 an air detector 52 is interconnected in the conduit 26downstream of the filter 50. The air detector 52 detects the presence ofair in the conduit means and generates a signal reflective thereof. Moreparticularly it detects the presence of air bubbles in the blood andsends a signal reflective of their presence via a conductor (not shownfor clarity) to the controller 44.

The system of FIG. 1 also includes a shunt 54 which is interconnected inthe conduit means between the inlet side of the pump 28 and the outletside of the pump 28. More particularly the shunt 54 is interconnected inthe tube 26 at one end 55 between the catheter 14 and the inletdetecting means 30 and more particularly the inlet pressure sensor 30.Similarly, the other end 57 of the shunt 54 is interconnected in thetube 26 between the air detector 52 and the catheter 36. A firstsolenoid valve means and more particularly a flow blocking device 56 ispositioned between the inlet catheter 14 and shunt 54. A second solenoidvalve means and more particularly a flow blocking device 58 ispositioned in the shunt 54. A third solenoid valve means and moreparticularly a flow blocking device 60 is positioned between the shunt54 and the outlet means or outlet catheter 36.

Upon receipt of a signal from the air detector 52 indicating thepresence of air in the blood in route to the outlet catheter 36, thecontroller 44 generates operating signals to operate the first, secondand third solenoid valve means and more particularly the flow blockingdevices 56, 58 and 60 so that the flow blocking device 56 moves from itsnormally open operating position to a closed position. Similarly, flowblocking device 58 receives its operating signal from the controller 44to move from its normally closed condition to an open condition in whichflow through the shunt 54 is permitted. At the same time the third flowblocking device 60 moves from a normally open position, in which bloodflows through the tube 26 to the catheter 36, to the closed condition.Therefore, the pump 28 urges blood through the blood treatment device 32and through the shunt 54 in the direction of arrow 62 and back to theinlet of the pump 28 as indicated by arrow 64. This condition ismaintained until the signal from the air detector 52 indicates thatthere is no air present in the tube 26, causing the first, second andthird flow blocking devices to return to an operating configuration inwhich the first and third flow blocking devices 56 and 60 are open andthe second flow blocking device 58 is closed to interrupt flow throughthe shunt 54. The air detection feature is intended to avoid introducingair accidently into the patient and thereby causing an embolism, withthe related risks of damage to the patient.

The system of FIG. 1 may further include a second pump meansinterconnected into the tube 26 for metering fluids into the blood inthe tube 26. In the system of FIG. 1, the second pump means is a syringe70 having an outer casing 72 and a piston or plunger 74 which ismechanically connected to a motor device 76. In operation the motor 76moves the plunger 74 inwardly 78 to meter fluids held within the syringe70 through tube section 82 into the tube 26 between the output 29 of theroller pump 28 and the upstream pressure sensor 46. The motor device 76is interconnected to control means 44 by a conductor (not shown forclarity) so that the device 76 may be operated to meter at a ratedesired by the user. It may be noted that the motor device 76 may be asolenoid or any other electrical device that would provide linear motionof sufficient force to drive the plunger 74 inward and in turn urge thefluid 80 through the tube section 82 into the tube 26 and moreparticularly the tube section 84 of tube 26 between the pump outlet 29and the upstream pressure sensor 46.

It may be noted that the controller 44 has a power supply 90interconnected therewithin to receive power from an external source hereillustrated to be 115 volt power from a conventional wall plug viaconductor 92. The power supply 90 in turn supplies power via conductor94 throughout the controller 44.

It may be also noted that the blood treatment means 32 may preferably bean oxygenation device which is connected to receive oxygen from a supplythereof 96 via a tube 98. That is, the blood treatment means 32 may be amembrane structure which receives the supply of oxygen and supplies theoxygen to the blood passing therethrough. Other types of blood treatmentdevices may also be suitable as more fully discussed hereinafter.

Roller Pump

FIGS. 2 through 5 illustrate the pump arrangement particularly suitablefor use in the system of FIG. 1. In FIG. 2, a roller pump 100 has ahousing 102 formed with a top 104, a bottom 106 and a front 108. Thehousing 102 has a keyhole-shaped recess 110 formed in the top 104extending inwardly into the housing 102. The recess 110 has a throat 112which has opposite sides 114 and 116. The opposite sides 114 and 116open through the front 108 and extend into the housing 102 to connectwith opposite ends 109 and 111 of an arcuate recessed surface 118.

The pump 100 has axle means rotatably secured to the housing 102 toextend into the recess 110. More particularly, the axle 120 (FIG. 4)extends into the housing 102 and more specifically into the recess 110to be centrally positioned within the recess 110 with respect to thearcuate recessed surface 118.

The pump 100 may be regarded as having a pump head means which isremovably secured to the axle means and positioned within the recess110. As illustrated in FIG. 2, the pump head means may include rollermeans positioned proximate the arcuate recessed surface 118 for urgingconduit means and more particularly tube 26 against the arcuate recessedsurface 118.

Referring specifically to FIG. 4, the pump head 122 is shown to includelocking means for removably securing the pump head 122 to the axle 120.The locking means includes an engagement portion and a latch memberpositioned for operation by the user and operable between a firstposition in which a latch member engages the engagement portion tosecure the pump head to the axle 120 and a second position in which thelatch member is disengaged from the engagement portion removably fromthe axle as more fully described hereinafter.

The pump of FIG. 4 further includes an adjustment structure interposedbetween the pump head 122 and the axle 120 for moving the pump headmeans 122 axially 124 toward 136 and away 138 from the axle 120 to inturn adjust the degree of pressure being exerted on the tube 126 and inturn the degree of volume of fluid being pumped through the tube 126.That is, operation of the adjustment structure causes the roller meansto move toward and away from the arcuate recessed surface 118 and inturn adjust the degree of squeeze or pressure being exerted against thetube 126 and further the volume output of the pump.

The adjustment means shown in FIG. 4 includes a follower 128 positionedto move toward and away from the axle 120. The adjustment means includesa screw arrangement 130 which has a head 132 accessible to the operatorwith threaded portions 134 interconnecting the follower 128 to the axle120 to move the follower toward 136 the axle 120. In operation, the head132 is rotated by the user by the use of, for example, a screwdriver.Operating the head 132 in the outward direction allows the spring 144 tocontact lip 142 to urge the follower 128 outwardly away from the axle120.

In reference to the locking means, it can be seen in FIG. 4 that anengagement portion is formed in the follower 128. More particularly, aslot 150 is formed in the follower 128 on both sides thereof as shown.Similarly, corresponding slot 152 is formed in a sleeve section 154 ofthe pump head 122. A key 156 slides into the key way or opening formedby the slots 152 and 150 which are positioned with respect to each otherto form the key way.

The key 156 is best shown in FIG. 8. The key has a tongue portion 160which extends outwardly away from the sleeve 154 for operation by theuser. The key 156 fits within the key way formed by the slots 152 and150 as stated before. The slot 150 in the follower 128 is shown indotted line in FIG. 8.

The key 156 is formed to have a keyhole-shaped opening 162 having athroat portion 164 and a circular or larger opening section 166. It canbe seen the arcuate or circular section 166 has a cross-section which indiameter 167 exceeds the diameter 169 of the follower 128. Accordingly,when the key 156 is positioned in the unlock condition with the largerportion 166 centrally about the follower 128 as illustrated in FIG. 8,the entire pump head 122 may be moved upwardly, leaving behind thefollower 128 and the axle 120. When the key 156 is positioned in thelock condition as shown in FIG. 8 the throat portion 164 is urged intothe key way and in particular the slot 150 so that relative movement isprevented. The external portion 168 interacts with the slot 152 whilethe internal portion 170 of the throat 164 interacts with the slot 150,to act in total to prevent relative movement between the key way and thefollower 128 and thereby locking the pump head 122 to the follower 128and in turn to the axle 120. The key 156 may have ears 172 and 174 toprevent excessive movement of the key 156 in an unlocking configuration.Alternately, the key 156 may be formed to snugly fit into the slot 152of the sleeve 154. The key 156 may be sized so the outer edge 168 of thekey 156 may fit snugly against the exterior outward surface of the slot152. In turn, the key 156 will remain secure in the sleeve 154 uponremoval of the pump head 122 from the follower 128.

Further, it may be noted that the pump head 122 has a top member 180 anda base 182 interconnected by the sleeve 154. As better seen in FIGS. 2,3 and 4 the top member 180 is an elongated section extendingtransversely and substantially symmetrically away from the follower 128.The upper member 180 has opposite halves 180A and 180B which arepositioned to extend opposite from each other in a substantiallysymmetric pattern to function as a transverse member or arm. The uppermember 180 is desirably secured to the sleeve 154 to rotate therewith.As best seen in FIG. 4, the upper member 180 is unitarily formed withthe sleeve. Alternately, the upper member may be secured thereto bywelding or other adequate mechanical securing arrangements.

As better seen in FIG. 4, the sleeve 154 is also unitarily formed withthe base 182. The base may also be separately formed and attached to thesleeve 154 if desired. Also, it may be seen in FIG. 4 that the sleeve ismade to snugly, but rotatably fit about the axle 120.

The rollers 184 and 186 are each secured between the base 182 and theupper member 180 at the outer ends 183, 185 of the upper member 180. Therollers are each formed to be conical in shape with an outer surfacesuch as surface 188 positioned to be proximate the arcuate recessedsurface 118 in the recess 110. Specifically, it can be seen in FIG. 4that the outer surface 188 of roller 184 is positioned to besubstantially in alignment with or substantially tangential to thearcuate recessed surface 118. The tube 126 is positioned between theouter surface 188 of the roller and the arcuate recessed surface to bepressed or urged against the surface 118 by the roller 184. Uponrotation, the roller 184 rolls over the tube 126 squeezing it asillustrated in FIG. 4 and thereby urging liquid or fluid in the tube 126therethrough. A positive displacement pumping action is effected.

It may be noted that the recessed arcuate surface 118 is formed in thehousing 102 to angulate inwardly toward the axle 120. As shown in FIG.4, the surface 118 is positioned at a angle 192 with respect to the axle120 and the axis 124 of the axle. Similarly, the rollers 184 and 186 areeach positioned so that the outer surfaces thereof 188 and 190 each aresimilarly angulated with respect to the axis 120. As shown in FIG. 4 therollers 184 and 186 are positioned at a angle 193 selected so that theouter surfaces 188 and 190 are in alignment with and substantiallytangential with the recessed arcuate surface 118.

The upper portions of the rollers 184 and 186 each have an upper surface194 and 195 which extends from the outer end 183 and 185 respectivelytoward the top 104 of the housing 102 to avoid a protrusion and also tofacilitate positioning of the tube 126 into the recess 110.

Notably, the rollers 184 and 186 are each rotatably secured between theupper member 180 and the base 182. As shown in FIG. 4, roller 184 isrotatably positioned between upper member 180 and the base 182 by axle196 which is inserted through the upper member 180 near its outer end183 and threadably secured into the base 182. Interpositioned betweenthe upper member 180 and the roller 184 and also between the base 182and the roller 184 are wear surfaces such as bearings 200 and 202. Thebearings 200 and 202 are positioned and held in place by the axle 196.Roller 186 is similarly secured by an axle 198 extending through uppermember 180 into the base 182. Wear surfaces such as bearings 204 and 208are similarly held in place by axle 198.

In FIG. 4, it is also shown that the axle 120 has a bearing or bushing210 interpositioned between the axle 120 and the underside 106 of thehousing 102. In particular the axle 120 has a flange 211 which extendsoutwardly to contact the bushing or bearing 210. It may be further notedthat the axle 120 has a shaft 220 centrally positioned therein which isconnected to the drive means for rotation. The shaft 220 is held inplace by one or more set screws such as set screw 222.

Referring to FIGS. 2 and 3, it can be seen that a number of fingers 230,232, 234 and 236 extend outwardly from the sleeve 154 to which they aresecured. Fingers 230 and 232 are each positioned proximate to and onopposite sides of roller 186. Similarly, fingers 234 and 236 arepositioned to extend on opposite sides of roller 184. It has been foundin operation that the tube 126 tends to ride upwardly or outwardly alongthe arcuate recessed surface 118. The fingers 230, 232, 234 and 236 areeach sized to extend away from the sleeve 154 to proximate the arcuaterecessed surface 118 thereby extending over the tube 126 as better seenin FIG. 3. Therefore, if the tube 126 does tend to ride upwardly oroutwardly from the recess 110, it will come into contact with thefingers 230, 232, 234 and 236 to hold tube 126 in the recess 110.

The upper member 180 is here formed to have a handle 240 rotatablysecured thereto to rotate between an extended position, such as thatshown in FIG. 5, and a secured or stored positioned such as that shownin FIGS. 2 and 3. The handle 240 is rotatably secured to the uppermember 180 by an axle or pin 242 which extends through the handle 240and the upper member 180 and more particularly the section 180A of theupper member of 180. The handle 240 is secured to the upper member 180by pin 246 which interconnects with an aperture 244 formed in thesection 180B of the upper member 180. The handle 240 may thus be rotatedbetween the upright position such as that shown in FIG. 5 and the secureposition such as that shown in FIGS. 2 and 3. In the secure position thepin 246 will interact with the aperture 244 to secure the handle inplace.

Notably, the handle 240 is "U" shaped and sized to snugly fit about theupper member 180 including the follower 128 which has a flat 247 formedto accommodate the handle 240. The handle 240 is positioned so that whenextended it is spaced from the axis 124. Thus, it may be grasped by theuser to rotate the pump head 122 and specifically the rollers 184 and186 to effect pumping action manually in the event of electrical failureor component failure.

As seen in FIG. 2 the motor 248 is interconnected to a gearingarrangement 294 from which the shaft 220 extends into the axle 120. Useof a high speed servomotor 248 and a gearing arrangement 294 permitsprecise control of the rotation rate of the pump. A brushless dc motormodel FH-BDC and a gear head FH-GB made by Robbins-Myers of Gallipolis,Ohio is presently used for the pump 100 and gearing arrangement 294.

The front 108 of the housing 102 has a block 250 positioned thereinabout shoulder 252. The block 250 is secured in place by a screw 254which operates to adjust the block inwardly and outwardly 256 withrespect to the housing 102. More particularly, the block 250 has anouter surface 258 which is positioned to be in alignment with thesurface 116 of the throat 112. Movement of the block 250 inwardly andoutwardly 256 adjusts the contact between the surface 258 and the tube126. The surface 258 clamps or squeezes the tube 126 against the surface116 at the outer edge 260 of the surface 116. Similarly, the block 250operates so that its surface 264 squeezes the tube 126 against thesurface 114 proximate the outer edge 262. In operation, the screw 254can be operated to vary the degree or amount of friction or the amountof clamping action effected by the block 250 against the tube 126.Notably, the tube 126 is partially positioned within correspondingrecesses 290 and 292 formed in the surfaces 114 and 116.

In FIGS. 6 and 7, an alternate arrangement is illustrated in which thehousing 270 has a throat 272 with an opening 274. A track or rail 276 ispositioned along the lower surface 278 in the opening 274. A block 280has an opening 282 which is here shown to be "T" shaped and configuredto slidably and snugly fit along the track 276. The block 280 ispositioned over the track 276 so that its outer surface (not shown)similar to outer surface 264 of block 250 can interact against thesurface 283 of throat 272 at the outer edge 284 substantially the sameas illustrated in FIG. 2. The screw 286 may be used to secure the block280 to the track 276.

It may be noted that the pump 100 has two rollers 184 and 186. It shouldalso be understood that an arrangement with three or more rollers can bedevised depending upon the pump volume required by the user at a givenrotation rate.

Pressure Sensor

Referring now to FIG. 9 a pressure sensor for use in the system of FIG.1 is illustrated. It here has an interconnect section 300 forinterconnection into the conduit means and more particularly tube 26.The interconnect section 300 is here shown to have an inlet 302 and anoutlet 304. However, it may only have an inlet in other applications.The inlet 302 and outlet 304 have respective flange connectors 306 and308 for a friction connection to a flexible tube which is tube 26. Anaperture 310 is formed in the interconnect section 300 with a membrane312 positioned therein. A housing 318 is positioned about the membrane312 and aperture 310. The housing contains a fluid 314 therewithin.Fluid pressure in the interior 316 of the interconnect section 300 isreflected to the fluid 314 in the interior of the housing 318.

Positioned within the housing 318 is a plunger 320 which operatesbetween a first position in which it is in contact with the membrane 312to urge the membrane 312 into the interior 316 of the interconnectsection 300, and a second position where the plunger 320 is spaced awayfrom the membrane 312. As here shown, the plunger 320 has an arcuate ormushroom-shaped head 322 with a shaft 323 extending therefrom. Asolenoid 324 is positioned around the shaft 323 to urge the shaft 323inwardly and outwardly 315 and in turn the head 322 between the firstposition and the second position as stated.

A spring 326 is desirably interconnected between the solenoid 324 and aflange 328 associated with the shaft 323 to urge the shaft 323 and inturn the head 322 away from the membrane 312 to a second position fornormal membrane operation.

A port 330 is formed in the housing 318 to which a pressure sensor 332is sealingly interconnected. The pressure detector 332 has a opening 334to the atmosphere for calibration purposes. It is conductively connectedvia conductor 336 to an external control means such as controller 44 ofFIG. 1. In use, the solenoid 324 is activated via conductor 337 to causethe plunger 320 to be urged against the membrane. In this position, thedetector 332 can be calibrated since the maximum distention of themembrane is a known quantity for purposes of zeroing the sensor of FIG.9.

In operation, the fluid in the interior 316 of the interconnect section300 will vary in pressure and in turn cause the membrane 312 to flexinwardly and outwardly 314. These pressure variations are thus reflectedat the port 330 and sensed by the detector 332. Signals reflective ofthe pressure variations are transmitted via conductor 336.

Clamping Device

As noted in FIG. 1, solenoid means are used in order to block fluid flowthrough tubing 26. Fluid flow blocking devices 56, 58 and 60 areemployed to regulate flow in the system between a normal condition andsituations in which flow must be interrupted to the patient because ofthe detection of air by air detector 52. A number of different solenoiddevices may be used. In FIGS. 10A, 10B and 11 a bridge clamp isillustrated to act as the solenoid means and more particularly the fluidflow blocking devices 56, 58 and 60 of FIG. 1.

As shown in FIG. 10A, a base 350 has a motor 352 secured thereto byscrews 354 and 356. An axle 358 extends away from the motor and awayfrom the base 358. A housing 360 is secured to the axle 358 by set screw362 to rotate therewith. The housing 360 also has a upper member 364secured thereto to form an upper finger 364 and a lower finger 366. Aroller 368 is rotatably secured between the upper and lower fingers 364and 366 as shown in 10A. In particular, the roller 368 is secured at adistance 369 spaced away from the axle 358 to be proximate a pin 370which is also secured to the base 350. The tube 126 is here shown in acollapsed condition 374 interspaced between the finger 370 and theroller 368 to interrupt flow through the tube 126 also as shown in FIG.11. That is, when the roller 368 is in the closed position asillustrated in FIG. 11 and in FIG. 10A, fluid flow through the tube 374is interrupted because the tube 374 is effectively clamped off.

As can be seen, the finger 370 is spaced away from the axle 358 adistance 372 which is selected in relation to the distance of the roller368 so that the clamping action will be effected when the roller 368 isput in the closed position. Upon operation of the motor 352 the clamp isrotated away from the pin 370 to an open condition. Notably, the roller368 is rotatably secured between the fingers 364 and 366 by a shaft 376.

It may also be noted that the clamp is operable by the user by operatinghandle 380 which is secured to the finger 364. That is, the handle 380has a body 376 which is secured to the upper finger 364. In the event ofa electrical failure, system malfunction or failure of the motor 352 theoperator may grasp the handle 380 and rotate the roller from the closedposition to the open position as shown in FIG. 11.

Controller

FIG. 12 is a block diagram of the controller 44 as illustrated inFIG. 1. The controller of FIG. 1 is not shown with interconnectingconductors to the various sensors. Those conductors have been eliminatedin order to clarify the illustration.

Referring to FIG. 12, a microprocessor board 510 is configured toreceive an input from a pressure sensor such as pressure sensor 30 inFIG. 1 via conductor 512 through an isolating pressure amplifier 514.The input signal is then processed by a buffer amplifier as illustratedto be received by the microprocessor board 510. Similarly, input signalsare received from the upstream pressure sensor 46 via conductor 516 andthe downstream pressure sensor 48 via conductor 518. Signals are alsoreceived from a temperature detector via conductor 520 optionallypositioned proximate to the blood treatment means 32. The signals fromthe air detectors may also be received via conductor 522. All the inputsignals are processed by respective buffer amplifiers before beingtransmitted to the microprocessor 510.

The power supply 90 of the controller 44 is illustrated to receive 115volt AC power from a wall outlet via conductor 500. The power isprocessed through an AC to DC converter 502. The DC power is transmittedto a battery charger 503 to either an emergency battery (not shown) or aDC converter 504. The output current is monitored by sensor 506 as anexcessive current drain would indicate failure of some component or astalled pump controller. For example, FIGS. 14 through 23 show variouscircuits and components in which 5 volt signals are applied to operatecircuits and chips within the controller 44.

Referring again to FIG. 12 the microprocessor board 510 is shown havingan output to a display driver 524 which in turn supplies the controllerdisplay 526 illustrated in FIG. 13. Similarly the microprocessor board510 receives an input from the display of FIG. 13 and more particularlythe keys or operating buttons 528 thereof through a buffer amplifier530. The microprocessor board 510 supplies an output via driver 532 tooperate the clamps 534 and more particularly the flow blocking devices56, 58 and 60 of FIG. 1. The microprocessor board 510 also supplies anoutput to a motor controller 536 which in turn operates the roller pump538. The roller pump itself supplies a feedback signal back to themicroprocessor board via conductor 540.

Referring now to FIG. 13, the operation panel 549 of the controller 44is shown configured into a series of sections. The pump control section550 includes a indicator 552 which shows speed in revolutions per minute(RPM) or flow in liters per minute (LMP). The indication may be selectedby operation of switch 558 between the flow position and the RPMposition. The speed of the pump (e.g. pump 28 or pump 100) may beregulated by operating of the up switch 554 indicated by an up arrow orthe down switch 556 indicated by the down arrow. Also, the pump (e.g.,pump 28 or pump 100) may be turned on or turned off by operation of theactivation switch 560.

The controller 44 operation panel 549 also has an inlet pressure section562. A preselected set point pressure of the inlet pressure sensor 30 inmillimeters of mercury (mmHg) is shown on the display 568. Thepreselected set pressure may be adjusted by operation of the up switch564 and the down switch 566. Similarly, the control panel of FIG. 13 hasa premembrane pressure section 570 which shows the set point of theupstream pressure sensor 46 that is selected by operation of the upswitch 571 and the down switch 569. The pressure is displayed inmillimeters of mercury (mmHg). In similar fashion, the post membranepressure section 572 illustrates the set point of the downstreampressure sensor 48 of FIG. 1. The set point may be adjusted by operationof the up switch 573 and the down switch 575.

In operation, the temperature of the blood treatment device 32 (FIG. 1)may be indicative of its operation as well as indicative of thetemperature of the blood being returned to the patient. Thus, it may bedesired to position a temperature sensor proximate the blood treatmentdevice 32 to compare the temperature (in degrees centigrade) to a setpoint temperature selected by operation of the up switch 577 and thedown switch 579.

The control panel 549 also has an alarm section 576 which has pluralityof light emitting diodes (LED's) such as LED 578 which is illuminatedwhen the pressure of the inlet pressure sensor 30 exceeds thepreselected pressure selected and shown in the display 568. Similarly,LED 581 and LED 583 show the presence of an alarm condition in the eventthe upstream pressure sensor 46 and downstream pressure sensor 48 sensea pressure which exceeds that indicated and preset in the displays ofsections 570 and 572 respectively. The LED 585 will activate upondetection of air in the tube 26 by detector 52. LED 580 is illuminatedupon deactivation of the air detector 52 by operation of switch 594 onthe control panel section 590. Similarly, if the pump motor fails (e.g.motor 248, FIG. 2) LED 582 activates. A cover (not shown) may beinstalled over the pump in which case, LED 587 will activate in theevent the pump cover is removed. A battery failure is indicated by theLED 589; and an overall system failure is indicated by the LED 591. Anaudible alarm may be associated with the activation of any one of theLED's above described. The audible alarm may be silenced by operation ofthe mute switch 584.

Power to the overall system is controlled by the "on" switch 586. Thesystem of FIG. 1 may be manually operated or operated in automatic. Inmanual, the user may manually control the system by operating the pumpmanually through the use of handle 240 (FIG. 5) with the pump offthrough operation of the on/off switch 560 in the pump control section550. The pump may also be electrically operated in the manual mode byoperation of the switch 560 to the "on" condition. In the manual mode,the air detector 52 may be similarly turned on or off particularly whenthe system is being primed for operation. That is, in order to start upthe system, air may be present in the system. Initial start up to flushout the air may be desired before connecting to the patient.

The flow blocking devices 56, 58 and 60 may also be activated ordeactivated by operation of the switch 596. In some circumstances, theuser may elect to place the system in a safe condition by isolating thepatient from the system. In that situation the bridge clamp switch 596may be operated. Upon operation, the flow blocking devices 56 and 60proceed to their closed condition and flow blocking device 58 goes to anopen condition. The calibrate switch 593 is used to calibrate thepressure sensor 30, the upstream pressure sensor 46 and the downstreampressure sensor 48.

Referring now to FIG. 14, a watch dog circuit 598 is shown connected toreceive an input from a peripheral board 630 via conductor 600. Thewatch dog circuit 598 employs a low frequency oscillator 602. Theoscillator 602 is interconnected to a buffer 604 to intermittently sendsignals through the inverter 606 to the "and" circuit 608 to in turnperiodically supply a reset signal 610 to the microprocessor. Unless thebuffer 604 is reset periodically by the microprocessor 625 via line 600,the microprocessor is reset to 0 via 610 to avoid the risk of anambiguity where the microprocessor is locked in a cycle from which itcannot escape. The power on and reset circuit 612 is also shown in FIG.14 supplying an input to the "and" circuit 608.

FIG. 15 is a clock circuit which supplies a clock signal to themicroprocessor. The clock circuit 614 has an oscillator 620 whichsupplies an output to a divider 622 and a shift and divide circuit 624.The output of the divider 622 is supplied via conductor 618 to themicroprocessor. The output of the shift divide circuit is supplied tothe microprocessor via conductor 616.

FIG. 16 shows the microprocessor board with the microprocessor chip 625receiving inputs from the reset circuit via conductor 610 and from theclock circuit 614 via conductors 616 and 618. The microprocessor 625 isinterconnected to an eprom or erasable, programmable memory 626 and arandom access memory (RAM) 628. The microprocessor chip 625 is alsoconnected to a standard peripheral circuit 630. The peripheral circuit630 is also connected to standard communication port 632.

Referring now to FIG. 17, inputs from the pressure transducer amplifierof FIG. 12 are received by the multiplexor 632 and supplied to a singleanalog to digital (A/D) converter 634. The A/D converter 634 suppliesits output to a bus which is controlled by a bus driver 636. The busdriver 636 processes signals to and from input/output ports such as port632. Inputs are received by the bus driver 636 via port circuits 634 and636 for further processing by the microprocessor. Input and output portsare selected by decoders 638 and 640.

Referring now to FIG. 18, the display circuit 646 is shown with inputsfrom the various detectors received and supplied to various indicatorswhich are here shown. For example, the flow indication is displayed byLED displays 648A, B, & C. Similarly, the pressure set point of theinlet pressure sensor 30 is displayed by the LED display circuits 650A,B, & C. The temperature set point of the blood treatment device 32 isdisplayed by LED display circuits 652A, B & C. Similarly, the pressureset point of the upstream pressure sensor 46 is shown on the LED display654A, B, & C. The set point of the downstream pressure sensor 48 isdisplayed on the panel section 572 shown in FIG. 13 by LED displays656A, B, & C. All of the LED displays 648, 650, 652, 654 and 656 areinterconnected to a microprocessor-compatible LED driver 658, 660, 662,664 and 666 respectively. Interconnected between the drivers 658, 660,662, 664 and 666 and the LED displays 648, 650, 652, 654 and 656 arecurrent limiting resistor banks. The LED display arrangement isinterconnected by decoder 644 through a connection panel 642 furtherinterconnected to the microprocessor.

FIG. 19 shows the circuitry associated with the panel switches of FIG.13. The switches 678 are arranged with a power-on-reset function so thatupon activation, the power-on-reset amplifier 674 resets all of thelatches to their normal off or on position preselected by the user.Thereafter activation of switches 678 causes operation of the inverter680 and further activation of the latches such as latch 676. The outputof the manual switches 678 is supplied through a buffer driver 684 whichturns on and off to read the status of the latches 676. Similarly,buffer drivers 682 and 672 turn on and off to read the status of theswitch bank 670. The output of the drivers 682 and 672 is supplied tothe data bus of the microprocessor 625 (FIG. 16).

Referring now to FIG. 20 the LED array shown in the alarm section 576 ofFIG. 13 is shown in greater detail. The LED's of FIG. 13 are shown withtheir corresponding inverter/driver. Referring now to FIG. 21, a desiredcircuit for use as a motor speed control is shown. The circuit is shownin the block diagram of FIG. 12 as circuit 536. Referring now to FIG. 22a desired pressure transducer amplifier is shown for use in associationwith pressure sensors 30, 46, and 48 of FIG. 1. Similarly, the outputsignal buffer is shown in FIG. 23 as the buffer amplifier of FIG. 12.

Referring now to FIGS. 24 through 29, the architecture of the softwareor program in the microprocessor 625 is illustrated. Symbols include thesymbol AVGPRS which means average pressure. Also shown is the symbolMTRSPD which means motor speed. The symbol MAXSPD stands for motormaximum speed. The symbol AVGPLO stands for average pressure of a samplewhich the zero sample.

The expression or letter "D" refers to a scratch pad holder in themicroprocessor 510 in which calculations are made. The servo flow chartof FIGS. 24-29 shows automatic operation of the system of FIG. 1.

Components

The components in the system of FIG. 1, have been selected to beparticularly suitable for an extracorporeal support system and moreparticularly an extracorporeal membrane oxygenator. For example, thefirst solenoid valve means is not a commercially available device, butrather is a bridge clamp or a flow blocking device illustrated anddescribed with respect to FIG. 10A, 10B and 11. Similarly, the secondsolenoid means 58 and the third solenoid means 60 are also flow blockingdevices illustrated with respect to FIGS. 10A, 10B and 11.

The inlet pressure sensor 30 as hereinbefore discussed is similar tothat illustrated and discussed with respect to FIG. 9. The pump 28 is apump similar to the pump 100 illustrated and described in FIGS. 2-8. Thesecond pump means 70 is a standard syringe which is constructed to bepositioned on a base 77 with motor operation device 76 as hereinbeforediscussed. The controller 44 is separately manufactured and assembled asdiscussed with respect to FIGS. 14-29. The upstream and downstreampressure sensors 46 and 48 are preferably pressure sensors of the typeillustrated and described with respect to FIG. 9.

The filter 50 in the system of FIG. 1 is preferably a 20 micron arterialfilter, model K37, made by Healthdyne Cardiovascular of Marietta, Ga.The air detector is an ultrasonic scatter detector presently made byZevex of Salt Lake City. The blood treatment device is preferably ablood oxygenator which may be a 0.6 square meters or 0.8 square metersmade by Scl-Med of Minneapolis, Minn. Larger sizes are available foradults. The system blood treatment device may also be a CO₂ removalstructure. It may also be configured for cardiopulmonary support or fullbypass as well as organ preservation.

The tube 26 is preferably a Tygon® tubing of a medical grade readilyavailable. It has been described as a single piece of tube proceedingbetween the connector 24 of the inlet catheter 14 and the connector 39of the outlet catheter 36. It may also include separate tube segments,such as segment 400, 402, 404, 84, 406, 408, 410, 412, 414 and 416.Notably, segment 404 and 84 are in fact one length of tubing because itis threaded through the pump 28 as better shown by tubing 126 which isthreaded through the recess 110 of pump 100 of FIG. 2.

Operations

In operation the system of FIG. 1 is operated by first positioning asystem such as that illustrated in FIG. 1 near the patient 10. Blood istypically inserted into the system by operation of the pump 28 andconnection to an external supply of blood particularly if the patient isa small patient such as a neonate. The system is operated to remove allair. Connection is made to the inlet catheter 14 positioned as discussedwith respect to FIG. 1. The outlet catheter 36 is positioned asdiscussed with respect to FIG. 1. System operation may first beinitiated in the manual mode, in which the operator manually operatesthe pump in order to initiate blood flow through the system to extractand supply blood to and from the patient at a reduced and manuallycontrolled rate, while the patient and the patient parameters such astemperature, blood pressure and respiration are monitored to make surethe patient remains stable. Assuming the patient remains stable, setpoints are entered on the operation panel of FIG. 13 and automaticoperation may thereafter be initiated by operation of the appropriateswitches on panel 549.

When the support system of FIG. 1 is placed in the automatic mode, itmay be regarded as being in the automatic servo mode. That is, the motordriving roller pump 28 such as motor 248 driving pump 100 (FIG. 2) ispreferably a servomotor. Upon initiation of automatic operation, themaximum pump speed for the average pressure for the inlet pressuresensor 30 is recorded. These values thereafter can be changed only byreturning to the manual operation mode to input changes by operation ofthe required or respective push buttons on the panel illustrated in FIG.13.

It is believed that if the average pressure sensed by the inlet pressuresensor 30 falls below a preselected pressure then the patient's bloodflow from catheter 14 is being reduced. This is interpreted by themicroprocessor 510 as a indication of excessive pump speed with the riskof completely emptying the right atrium or vena cava 18 of the patient10. As a result, the microprocessor 510 generates an output signal whichcauses the servomotor 248 to slow down until the slope of the pressuredrop sensed by the inlet pressure sensor 30 falls to 0 or the rollerpump speed/servomotor speed is 0. The microprocessor 510 attempts tooperate the servomotor at the maximum speed without inducing a drop inthe average pressure in the automatic operation.

In automatic operation, the upstream pressure sensor 46 supplies apressure signal which the microprocessor interprets to generate an alarmif the pressure sensed exceeds the preselected pressure entered on panel549. In operation it is believed that an increased pressure suggests ablockage in the blood treatment device; and such blockage may bedangerous if it becomes excessive. If an excessive pressure continuesfor a period in excess of 5 seconds the roller pump 28 is turned off andthe alarm continues to sound until deactivated by the user or thecondition is corrected by the user.

The downstream pressure sensor 48 sends its signal to the microprocessor510 which compares it with a preset or preselected pressure. If thesensed pressure is greater than the preset pressure then an alarmcondition exists and the alarm is activated on the panel section 576 ofFIG. 13. The roller pump 28 is first reduced to half-speed and after 5seconds turned off if the condition is not rectified.

Further, in operation, it may be desired first to 5 position the systemproximate the patient. As discussed, the presence of a inlet pressuresensor 30 on the upstream side 64 of the pump 28 and positioning of thedistal end 16 of catheter 14 in the right atrium or vena cava 18 of thepatient 10 permits selection of substantially a shorter length of tube26. As a result the system of FIG. 1 is more easily assembled fortransport of the patient in any context including emergencytransportation by airplane, helicopter or the like.

In operation, the microprocessor is set to automatically flush the shunt54 every 15 minutes to avoid coagulation and clotting in the shunt 54.That is, the blocking devices 56 and 60 close and blocking device 58opens for about 15 seconds every 15 minutes.

It should appreciated that the illustrated embodiments are merelyillustrative of the principles of the inventions which are disclosed.Specific reference to details thereof is not intended to limit the scopeof the claims which themselves recite those features of the inventionswhich are regarded as essential thereto.

I claim:
 1. A roller pump comprising:a housing having a top and abottom; a recess formed in said housing with a surface extendinginwardly from the top of said housing; axle means adapted to saidhousing in said recess to rotate relative to said housing; arm meanssecured to axle means to rotate therewith, said arm means includinglocking means for removably securing said arm means to said axle meansand said axle means including an engagement portion for engaging saidarm means, and further including a handle means having a first positionextending away from said arm means and a second position in which saidhandle means is positioned proximate said arm means; roller meanssecured to said arm means and positioned proximate said surface formovement therealong upon rotation of said axle means; adjustment meansinterpositioned between said axle means and said arm means for movingthe arm means and in turn said roller means; and a latch member movablebetween a first position in which the latch member engages theengagement portion to secure said arm means to said axle means and asecond position in which the latch member is disengaged from the saidengagement portion for removal of said roller means from said recess. 2.The roller pump of claim 1 wherein said surface is slanted toward saidaxle, wherein said roller means is a plurality of conical rollerspositioned proximate said surface with the exterior surface of saidrollers in substantial alignment with said surface of said recess. 3.The roller pump of claim 2 wherein said handle means is connectable tosaid arm means to extend away therefrom in said first position foroperation by the user to rotate said arm means.
 4. The roller pump ofclaim 3 wherein said handle means is hingedly secured to said arm meansand rotatable between said first and second positions.
 5. The rollerpump of claim 4 further including alignment members secured to andextending away from said axle means to proximate said surface in saidrecess.
 6. The roller pump of claim 5 wherein said housing has a front,wherein said surface is arcuate with a constant radius from said axlemeans, and wherein said recess includes a channel with opposite sidesextending from said front.
 7. A roller pump for pumping fluid through aflexible tube, said roller pump comprising:a housing having a top,bottom and front, said housing having a keyhole-shaped recess formed insaid top extending inwardly therefrom, said recess having a throat withopposite sides opening through said front interconnecting with oppositeends of an arcuate recessed surface, said flexible tube beingpositionable through said front in said recess along said arcuaterecessed surface; axle means rotatably secured to said housing andextending into said recess to be centrally positioned with respect tosaid arcuate surface; removable locking means for removably securingsaid pump head means to said axle means, said removable locking meansincluding an engagement portion and a latch member positioned foroperation by the user and operable between a first position in which thelatch member engages the engagement portion to secure said pump headmeans to said from axle means and a second position in which the latchmember is disengaged from said engagement portion and said pump head isremovable from said axle; drive means connectable to said axle means torotate said axle means relative to said housing; and adjustment meansinterpositioned between said pump head means and said axle means formoving said pump head means axially toward and away from axle means andin turn said roller means toward and away from said arcuate recessedsurface.
 8. The roller pump of claim 7 wherein said adjustment meansincludes a follower positioned to move toward and away from said axlemeans and screw means having a head accessible to and operable by theuser with thread portions interconnecting said follower to said axlemeans, said screw means being operable to move said follower toward andaway from said axle means.
 9. The roller pump of claim 8 wherein saidpump head means includes a sleeve for positioning over said follower andwherein said engagement portion includes a key way formed in said sleeveand said follower and wherein said latch is a key insertable into andremovable from said key way.
 10. The roller pump of claim 9 wherein saidarcuate surface slants toward said axle means, and wherein said rollermeans includes a plurality of rollers each conically shaped with anexterior surface positioned substantially tangentially proximate saidarcuate surface.
 11. The roller pump of claim 10 wherein said pump headmeans has a central member for connection to said axle means, a topmember connected to said central member, and handle means rotatablyconnected to said top member movable between a first position in whichsaid handle is extended away from said pump head means and operable forrotation of said pump head means and a second position in which saidhandle is positioned in a stored configuration proximate said topmember.
 12. The roller pump of claim 11 wherein said pump head meansincludes a base member secured to said central member and wherein saidroller means is a pair of said rollers positioned substantiallydiametrically opposite each other.